1. Field of the Invention
The invention relates generally to completion equipment and operations in subterranean wells and, more specifically, to a hydraulically operated sleeve valve that provides selective and controlled regulation of fluids within a tubing string in subterranean installations.
2. Description of the Related Art
Mechanical sleeve valves, such as BJ Services Company's family of Multi-Service Valves, are used in subterranean wells to provide zone isolation and bore completion control for completion operations such as gravel packing, spot acidizing and fracturing, killing a well, or directing flow from the casing to the tubing in alternate or selective completion operations. In such operations, the sleeve valve provides fluid communication between the tubing string, such as the inner diameter of the valve, and the outside of the valve, such as a well annulus. Typically, mechanical sleeve valves are opened or closed, such as by a shifting tool that is placed within the valve body and manipulated by standard wireline and/or coiled tubing methods. The sleeve, which seals the fluid communication path, can be physically moved from the closed to opened position, and vice versa, by these methods.
There also exist hydraulically actuated sleeve valves, such as WellDynamics' CC Interval Control Valve, in which opening and closing of the valve is achieved remotely with the use of two hydraulic control lines. In these types of hydraulic sleeve valves, a pressure differential across a defined piston area causes the sleeve to move in the desired direction.
Unlike mechanical sleeve valves, hydraulic sleeve valves typically do not provide a positive indication that the sleeve has been actuated to the fully opened condition or the fully closed condition. Debris, mechanical damage, and other such events or artifacts may prevent the valve from fully opening or fully closing at the rated pressure differential. Further, the oftentimes-severe conditions at the control site (such as, for example, sub sea) may allow precipitates to form in the control fluid (e.g., hydraulic oil) that may adversely affect opening or closing of the sleeve valve. Gases also may be introduced into the control lines, which also may adversely affect valve operation.
Applicants have invented an improved hydraulic sleeve valve that provides positive indication of the valve position, circulation of control fluid to eliminate or reduce control line contaminants, and/or positive alignment of the valve flow ports.